Various devices exist for removing pollutants, such as litter and sediment above 5 mm in size, from rainwater/stormwater runoff Examples include the gross pollutant traps (GPTs) disclosed in AU2004100956 and WO2007/030735. However, as known GPTs are configured for the removal of large pollutants in intense volume water flows, they provide limited removal of fine sediment and dissolved pollutants. Also, conventional GPTs contaminate the whole of the water flow to the highest level of any contamination passing through the system. Another problem with known GPTs is that settled contaminants in stormwater collected therein tend to be resuspended by subsequent stormwater inflow.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.